Posted by Sara on .
Dinitrogen pentoxide, N2O5, decomposes by firstorder kinetics with a rate constant of 0.15 s1 at 353 K.
(a) What is the halflife (in seconds) for the decomposition of N2O5 at 353 K?
(b) If [N2O5]0 = 0.0579 mol·L1, what will be the concentration of N2O5 after 4.0 s?
(c) How much time (in minutes) will elapse before the N2O5 concentration decreases from 0.0579 mol·L1 to 0.0143 mol·L1?

Chemistry 
DrBob222,
a. k = 0.693/t_{1/2}
b. ln(No/N) = kt.
No = given
N =?
k = from part a.
t = 4 s.
c.
same equation as b but
No = given
N = given
k = from a
t = ?
Note that part a is given in seconds, part c wants the answer in min.